The present invention relates to a work convey method and apparatus and, more particularly, to a work convey apparatus for conveying a top plate of a recording head for an ink-jet recording apparatus between a tray and a laser process machine.
FIG. 1 is a schematic perspective view showing an arrangement of a recording head of an ink-jet recording apparatus (bubble-jet recording apparatus).
A recording head 1101 has a liquid chamber 1130 for storing an externally supplied ink, and an array of a plurality of nozzles 1133. Each nozzle 1133 has an electro-thermal converter 1132 for generating thermal energy for forming an ink droplet to be discharged from a discharge port 1131 in accordance with image data.
The recording head 1101 is one adopted particularly in a bubble-jet recording apparatus among ink-jet recording apparatuses. The typical arrangement and principle of the bubble-jet recording apparatus are disclosed in, e.g., U.S. Pat. Nos. 4,723,129, 4,740,796, and the like, and can be applied to both so-called on-demand type and continuous type apparatuses. For example, an on-demand type bubble-jet recording apparatus will be explained below. The electro-thermal converters 1132 are arranged in correspondence with a sheet or a liquid channel (nozzles 1133), which holds a liquid (ink). Each electro-thermal converter 1132 generates thermal energy according to a drive signal, thereby causing film boiling on a heat application surface of the recording head 1101. As a result, a bubble having a one-to-one correspondence with the drive signal is formed in the liquid (ink), and the liquid (ink) is discharged as a droplet from the corresponding discharge port 1131 by expansion and shrinkage of the bubble. The drive signal to be supplied is preferably a pulse signal, as disclosed in U.S. Pat. Nos. 4,463,359, 4,345,262, and the like. As for the rate of temperature rise on the heat application surface of the recording head 1101, conditions disclosed in, e.g., U.S. Pat. No. 4,313,124 are preferably adopted.
In addition to the arrangement of the recording head 1101 shown in FIG. 1, the recording head used in the bubble-jet recording apparatus may adopt an arrangement wherein a heat application section is arranged in a bent region, as disclosed in, e.g., U.S. Pat. Nos. 4,558,333 and 4,459,600, or an arrangement wherein a slit common to a plurality of electro-thermal converters is used as a discharge section of the electro-thermal converters, as disclosed in, e.g., Japanese Patent Laid Open No. 59-123670, or an arrangement wherein apertures for absorbing a pressure wave of thermal energy are formed in correspondence with discharge sections, as disclosed in, e.g., Japanese Patent Laid-Open No. 59-138461. Note that in the above-mentioned recording head, a length corresponding to a predetermined width (the width of a maximum recording medium which can be used in recording by a recording apparatus) is assured by combining a plurality of recording heads. Alternatively, one recording head may be constituted to have a length corresponding to the predetermined length.
The above-mentioned recording head may be an exchangeable chip type head which is mounted on an apparatus main body to realize electrical connections (for electro-thermal converters) and supply of an ink, but may be a cartridge type head, as shown in FIG. 2.
FIG. 2 is a perspective view showing components of a recording head which is to be mounted on a base member of an ink cartridge for an ink-jet recording apparatus.
A recording head 1101 has, as its components, a heater board 1002 having a silicon substrate on which electro-thermal converters 1132 and, e.g., an Al wiring layer for supplying electrical power to the electro-thermal converters 1132 are formed by a film formation technique, a top plate 1010 in which nozzles 1133 and a liquid chamber 1130 are formed by a molding technique, and an ink tank 1004 for supplying an ink to the liquid chamber 1130 formed when the heater board 1002 is joined to the top plate 1010.
As shown in FIG. 3, the top plate 1010 is constituted by a top member 1011 formed with a plurality of nozzles 1133.sub.1 to 1133.sub.4 and a liquid chamber 1130, a planar member 1012 integrally formed on the front surface of the top member 1011 on the side of the nozzles 1133.sub.1 to 1133.sub.4, a projection member 1015 integrally formed on the top member 1011 on the side opposite to the planar member 1012, and formed with an ink supply hole 1014 for causing the liquid chamber 1130 to communicate with the ink tank 1004, and a plurality of slots 1013.sub.1 to 1013.sub.4 (only four slots are illustrated) formed in the planar member 1012 by a laser process machine, and serving as the discharge ports 1131 shown in FIG. 1. Note that the top plate 1010 to be actually used has a width of 7 to 8 mm, and is formed with 60 to 80 slots having an outer diameter of 20 to 40 .mu.m at intervals of 60 to 80 .mu.m.
In order to form the plurality of slots 1013.sub.1 to 1013.sub.4 in the top plate 1010, a work convey apparatus is used for conveying the top plate 1010 to the laser process machine from a tray storing a large number of non-processed top plates 1010. As the work convey apparatus, a conventional work convey apparatus which conveys a work by holding it by an auto hand may be used without any modifications.
However, when the conventional work convey apparatus is used without modifications, the following problems caused by the structure unique to the top plate 1010 shown in FIG. 2 are posed.
(i) When many top plates 1010 are stored in a tray as much as possible to improve a throughput, and the slots 1013.sub.1 to 1013.sub.4 are formed in a plurality of top plates 1010 at a time by the laser process machine, since the interval between adjacent top plates 1010 stored in the tray is different from that between adjacent top plates 1010 attached to the laser process machine, the auto hand must comprise a plural work holding mechanism, and a pitch conversion mechanism for converting the interval (pitch) between adjacent held top plates during conveyance.
(ii) In the process of the laser process machine, as described above, 60 to 80 slots having an outer diameter of 20 to 40 .mu.m must be formed at intervals of 60 to 80 .mu.m, thus requiring fine process precision. Therefore, when foreign matter becomes attached to a surface to be processed (a surface of the top member 1011 opposite to the projection member 1015) of the top plate 1010 or when the surface to be processed is damaged, the number of defective top plates 1010 is increased, resulting in a poor yield. Therefore, the top plates 1010 are preferably stored in the tray with the surfaces to be processed facing down. On the other hand, when the top plates 1010 are attached to the laser process machine, they are attached with the surfaces to be processed facing down, for the reason to be described later. Therefore, the auto hand must comprise a reverse mechanism for reversing the top plates 1010 during conveyance so that their surfaces to be processed face down.
(iii) When the slots 1013.sub.1 to 1013.sub.4 are formed in the top plate 1010 by the laser process machine, the slots 1013.sub.1 to 1013.sub.4 are formed to be located at the centers of openings of the nozzles 1133.sub.1 to 1133.sub.4. For this reason, as shown in FIG. 4(A), when the top plate 1010 is attached to a work station 1200 of the laser process machine, the surface to be processed of the top plate 1010 must face up. In addition, when the surface to be processed of the top plate 1010 is arranged to be parallel to the optical axis of the laser beam, holes are undesirably formed in a surface of the top member 1011 opposite to the planar member 1012. Thus, as shown in FIG. 4(B), the surface to be processed of the top plate 1010 must be inclined at a predetermined angle with respect to the optical axis of the laser beam. Therefore, the auto hand must comprise an inclination conversion mechanism for inclining the surface to be processed of the top plate 1010 at the predetermined angle during conveyance.
(iv) When non-processed and processed top plates are to be conveyed parallel to each other in order to improve a throughput, the pitch between adjacent processed top plates 1010, and the facing direction and inclination of the processed surfaces must be restored to a state suitable for storage in the tray. Therefore, another auto hand having a plural work holding mechanism, a pitch conversion mechanism, a reverse mechanism, and an inclination conversion mechanism similar to those described above must be arranged.